I might be able to release it tomorrow - I'll look into it

This is likely becuse your UV1/2/3 simply doesn't have the correct UV data. Try debugging with the UV node right into the emission input, and double-check the mesh importer to see if all channels are there

It could be because the UV coords are used to calculate all the tessellation parameters, which then could lead to seams

If it's a quick fix I'll push it out with SF 1.3, taking a look at it soon

Yep, this has been fixed in 1.29 :)

5.4 is supported, but was submitted through 5.3 because they're compatible so far

This is a setting in the texture itself. Set it to Clamp instead of Wrap

That's simply how alpha blending works, it's tricky to get it right in any game engine. It's a side-effect of not writing to the depth buffer, and conversely, writing to the depth buffer for transparent objects will lead to other side effects.

Generally it's cheaper to not branch, and instead render both and multiply the one with 0 and the other with 1, depending on your use case. It's also a question where you want to get the bool value from. What is true? Whether or not a value is beyond a certain threshold? For that, you can use the Step node. You might also want to look into the Toggle and Switch nodes

Actually, just found the issue! This has now been fixed in 1.29